A Validation Study of Four Preoperative Surgical Planning Tools for Adult Spinal Deformity Surgery in Proximal Junctional Kyphosis and Clinical Outcomes

BACKGROUND: Four guidelines have been suggested for optimal correction in adult spinal deformity surgery: Scoliosis Research Society (SRS)-Schwab classification, age-adjusted sagittal alignment goals, Global Alignment and Proportion (GAP) score, and the Roussouly algorithm. Whether these goals provide benefit in both proximal junctional kyphosis (PJK) reduction and clinical outcome improvement remains unclear. OBJECTIVE: To validate 4 preoperative surgical planning tools in PJK development and clinical outcomes. METHODS: We retrospectively reviewed patients who underwent ≥5-segment fusion including the sacrum for adult spinal deformity with a follow-up of ≥2-year. PJK development and clinical outcomes were compared among the groups separately using 4 surgical guidelines: SRS-Schwab pelvic incidence (PI)-lumbar lordosis (LL) modifier (Group 0, +, ++), age-adjusted PI-LL goal (undercorrection, matched correction, and overcorrection), GAP score (proportioned, moderately disproportioned, and severely disproportioned groups), and the Roussouly algorithm (restored and nonrestored groups). RESULTS: A total of 189 patients were included in this study. The mean age was 68.3 years, and there were 162 women (85.7%). There were no differences in the rate of PJK development and clinical outcomes among SRS-Schwab PI-LL modifier and GAP score groups. With the age-adjusted PI-LL goal, PJK developed significantly less frequently in the matched group compared with the under- and overcorrection groups. Clinical outcomes were significantly better in the matched group compared with the under- and overcorrection groups. With the Roussouly algorithm, PJK developed significantly less frequently in the restored group than in the nonrestored group. However, there were no differences in clinical outcomes between the 2 Roussouly groups. CONCLUSION: Correction according to the age-adjusted PI-LL goal and the restored Roussouly type was associated with reduced PJK development. However, differences in clinical outcomes were only observed in the age-adjusted PI-LL groups.